High-potential power supply



Jan. 1l, 1949. J. EVANS HIGH POTENTIAL POWER SUPPLY Filed July 2, 1945 ,WM5/V702. l JOHN C1/AMS TTO/VEV Patented Jan. 11, 1949 HIGH-POTENTIAL POWER SUPLY John Evans, Hightstown, N. .Lassignor to Radio Corporation of America, a corporationof Dela- Ware Application July 2, 1945, Serial No. 602,814

Claims.

The present invention relates to high potential power supplies and, more-particularly, to such :systems adapted for use with a load having low current requirements.

An object of the present invention is the provision of means for obtaining a high unidirectional voltage.

Another object of the present invention is the provision for a power supply -suitable for use with cathode ray tubes, linear accelerators, electron microscopes and the like.

A further object of the present invention is to provide a rectifier system for a high potential power supply operating at ultra high radio frequencies.

The foregoing objectsand others which may appear from the following detailed description can be obtained by providing a rectifier circuit utilizing coaxial transmission lines, each having an effective length` equal to one-quarter of the operating wavelength of the radio frequency oscillator to which it is connected and each short circuited at one end.

Still a further object of the present invention is the provision of a high Voltage power supply which is not dangerous to life.

A shorted quarter wave transmission line acts as a voltage transformation circuit, providing a voltage step-up proportional to the Q of the line. The term Q is an expression of the quality of the line, that is, the ratio of its resonant impedance to its resistance. Since it is entirely feasible to attain a Q" of several thousand in a coaxial transmission line, a substantial voltage step-up may be obtained without diiiiculty. Since current drain of the anode circuit of a cathoderay tube or electron microscope is low, the oscillator supplying the rectifier of present invention need be capable of supplying only a small amount of power.

A high voltage power supply, constructed according to the present invention, presents less danger to the unwary operator than conventional power supplies since the power supply is incapable of supplying appreciable current. Accidental contact with the high voltage terminal of the power supply presents such a drain on the system that the voltage drops to a value no longer dangerous to life.

.The present invention will be more fully understood by reference to the following detailed de-.`

scription which is accompanied by a drawing in which Fig. 1 illustrates in cross section an embodiment of the invention while Fig. 2 illustrates a modification of the invention shown in Fig. 1.

Referring now to Fig. 1 there is shown an annular evacuated casing I0. Within the casing Ill and coaxially arranged with respect to theoutside walls of the casing are a pair of inner conductors I2 and I4. Conductors I2 and I4, to-

gether with the outer casing l0, form sections of coaxial transmission lines each short circuited at one end. The lengths of conductors I2 and I4 are so chosen as to be one-quarter wave in length from point A where they are connected to the outer casing I il to their other ends where they are terminated in electron emitting means which may be iilamentary cathodes I5 and I6. One side of each of the filamentary cathodes is directly connected to the lconductors I2 and ifi while the other side is connected to lament leads I5 and i6' running within the conductors I2 and Ill. Near point A a hollow branch conductor 22 eX- tends through a vacuum tight seal 24 to the exterior. The filament lead extends through branch conductor 22 to the exterior of the systeml The distance, L, between the point of connection, X, of conductor 22 to conductor I2 and point A on the conductors I2 and I4 isso chosen as to match the characteristic impedance of the transmission line formed by conductor 22 and the outer surrounding shell 26. At the outer end of conductor 22 are arranged means for coupling the system to a source of high frequency oscillations which include a coupling loop 30 formed in conductor 22, said coupling being arranged to lie in inductive relationship with a tank circuit 32. The tank circuit may 'be connected to a high frequency generator means (not shown) of an appropriate frequency for operation with the rectier system of the invention. ISince one end of coupling loop 30 may be directly grounded or connected to the outer casing 26 of the input transmission line, the filament lead passing therethrough is effectively isolated from the high voltage system and may be connected to a conventional low voltage lament supply as indicated by the arrows. No elaborate insulation system is required for the filament supply system.

The entire system within casing In is connected to a vacuum system and exhausted to a pressure commensurate with the voltages involved.

Between the lamentary cathodes I5 and It is located an anode 34 which may be supported in position by. a support rod 36 passing through a vacuum tight bushing 38 to the exterior of the system where it is available as the high voltage negative terminal of the system. Supplementary or alternative anode supporting means may be employed as required. Also transformation conductors I2 and I4 may be supported Aby coaxial cable spacers or such similar means as may be required.

Since the device as so far described has, in effect, two one-quarter wave lines connected end to end, a total phase shift of is obtained between cathodes I5 and I6. Thus, a full wave rectifier is obtained from an unbalanced alterhating current source.

The voltage step-up obtained in the rectiiier circuit using one-quarter wave lines Ibeing pro- DOI'iOnal to the Q of the lines, it is desirable that the Q be made as high as possible. This is attained by an appropriate dimensioning of the ratios of the inner and o uter conductors to obtain a high characteristic impedance, however always bearing in mind the additional provision that the inner conductor diameter should be fairly large so as to minimize the ohmic resistance of the conductor itself. This necessarily follows since the Q of the line is proportional. to the quantity where Rc is the resistance of the conductor and Zo is the characteristic impedance of the line.

A modified form of the invention shown in Fig. 2 utilizes the same arrangement of inner conductors l2 and I4 as in Fig.1. However, the conductors are more closely adjacent and are contained within a cylindrical evacuating casing 50 instead of an annular casing as in Fig. 1.

The electron emission means or cathodes I5 and I6 are in this modification more closely adjacent than those in Fig. 1 and the anodeA 54 need not therefore be placed between the cathodes but may be positioned at one side thereof.

The filament heating arrangement, the means for supplying high frequency energy to the rectier and for withdrawing rectified direct potentials across load circuit 60 are the same as Fig 1 and need not again be described.

While I have illustrated a particular embodiment of the present invention, it should be clearly understood that it is not limitedA thereto since many modifications may be made in the several elements employed and in their arrangement and it is therefore contemplated by the appended claims to cover any such modifications as fall within the spirit and scope of the invention.

What is claimed is:

1. A power supply system. including means for coupling high frequency energy at low potential to said system, an evacuated casing having therein a pair of transmission line sections, eachA including a conductor having an electricalA length equal to one quarter of the operatingiwavelength of a source of; high frequency energy, with which said system is adapted to be operated, said line sections each being short circuited'. at oneend, said coupling circuit introducing said energyl into said lines near said one end, saidconductors each carrying an electron emittingV cathode at their free ends, and an anode structure inoperative association with said cathodes.

2. A power supply system including means for coupling high frequency energy at low. potential to said system, an evacuated casing having therein a pair of transmission line sections, each including a conductor having an electrical length equal to one quarter ofthe operating wavelength of a source of high frequency energy, with which said system is adapted tobe operated', said line sections each beingshort circuited at onel end; said coupling circuit introducing said4 energy into said lines near. said ends, said. conductors each carrying an electron emitting cathode attheir free ends, said endsbeing closely adjacent, and an anode in operative association-with saidcathodes.

3. A power supply systemv including a coupling circuit for coupling4 high frequency energy at low potential to said system, a pair of transmission line sections, each including aconductor having an electricalY length equal to` one quarter of the operating Wavelength ofl a source of; high 4 frequency energy, with which said system is adapted to be operated'saidyline sections each being conductvely connected. to; the other end, said coupling circuit coupling said energy into said lines near said one end, said conductors each carrying an electron emitting cathode at their free ends, said ends being closely adjacent, andan anode structure in operative association with said cathodes, said system being contained within an evacuated casing.

41.. A power supply system including means for coupling high frequency energy at low potential to said system, a pair of transmission line sections, each including a conductor having an electricall length equal toA one quarter of the operating wavelength of. a source of high frequency energy with. which said systernv is adapted to be operated, one of the ends. ofi said line sections being connected tov a common. point, means for coupling said. energy into, said lines near: said ends, said conductors each carrying anelectron emitting cathode at their free ends, said ends being closely adjacent, and an anode in operative association with` said cathodes, said system being contained within an evacuated casing, said casing serving as an outer shell for said. transmission` line sections.

5. A power supply system including means for coupling high frequency energy at low potential to said system, a pair of transmission line sections, each including a conductor having an electrical length, equal to one quarter of the operating wavelength of a source of high frequency energy, with which4 said system is adapted to be operated, said. line sections being conductively connected each tothe other at one end, means for coupling said energy into saidflines near said one end; said: conductors each carrying an electron, emitting cathode at their free ends, said free ends being closely adjacent, an anode in operative association withisaid cathodes and a connectionforenergizing said cathodespassing through said transmission line sections.

6. A4 power supply system includingI means for coupling; highA frequency energy at lowv potential to said` system, av pair ofi transmission line sectionseach including a conductor'having anrelectrical; length equal: to one quarter of the operating wavelength of: a source of' high frequency energy with whichsaidsystem is adaptedto'be operated; onev of the ends of said line sections being connected. to` ai, common point, means for couplingsaid energy intosaidilines near said one end, said conductors each carrying an electron emitting; cathode at their free ends, said free ends beingclosely adjacent', and an anode in operative association` with said! cathodes, said system beingcontainedswithin an evacuated'casing, said' casing serving` as anv outer shell'y for said transmission' linesections and a connection for energizing. said` cathodes passing through said transmissioni line,- sections.

7. A power supply system including a; hollow annular-casing, av pair ofinner conductors within said; casing and coaxially arranged withr respect',` to` the wall ofsaid casing, each. ofi said conductors having a` length equalY to one quarter of the wavelengthl off high frequency energy with which said system is adaptedI to be operated, said conductors having their endsclosely adjacent, one pair of: adjacent ends` being' connected' together andfto-said casing, the-other ends bearing electron emissive cathodes, an anode between said cathodes, aV coaXialline-section having, an inner conductorl connectedto one of said conductors near the end which is connected to said casing and an outer shell of said line section being connected to said casing.

8. A power supply system including a hollow annular casing, a pair of inner conductors Within said casing and coaxially arranged with respect to the wall of said casing, each of said conductors having a length equal to one quarter of the wavelength of high frequency energy with which said system is adapted to be operated, said conductors having their ends closely adjacent, one pair of adjacent ends being connected together and to said casing, the other ends bearing electron emissive cathodes, an anode between said cathodes, a coaxial line section having an inner conductor connected to one of said conductors near the end of which is connected to said casing, an outer shell of said line section being connected to said casing, and means for energizing said cathodes including a connection passing through each of said inner conductors from said cathodes to the exterior of said system.

9. A power supply system including a hollow annular casing, a pair of inner conductors within said casing and coaxially arranged with respect to the wall of said casing, each of said conductors having a length equal to one quarter of the wavelength of high frequency energy with which said system is adapted to be operated, said conductors having their ends closely adjacent, one pair of adjacent ends being connected together and to said casing, the other ends bearing electron emissive cathodes, an anode between said oathodes, a coaxial line section having an inner conductor connected to one of said conductors near the end which is connected to said casing, an outer shell of said line section being connected to said casing, and means for energizing said cathodes including a connection passing through each of said inner conductors from said cathodes to the exterior of said system, said casing being hermetically sealed and evacuated.

10. A power supply system including a hollow cylindrical casing, a pair of parallel hollow conductors having a length equal to a quarter of the wavelength of high frequency energy with which said system is adapted to be operated, said conductors being connected 'together and to said casing at one end, the other ends bearing electron emissive cathodes, an anode in operative relationship with said cathodes, an input circuit for said system including a coaxial line section having an outer shell branched from said casing and a hollow inner conductor connected to one of said pair of conductors near their connection to said casing and means for energizing said cathodes including connections from the exterior of said casing passing through said hollow conductors to said cathodes.

11. A power supply system including a hollow cylindrical casing, a pair of parallel hollow conductors having a length equal to a quarter of the wavelength of high frequency energy with which said system is adapted to be operated, said conductors being connected together and to said casing at one end, the other ends bearing electron emissive cathodes, an anode in operative relationship with said cathodes, an input circuit for said system including a coaxial line section having an outer shell ybranched from said casing and a hollow inner conductor connected to one of said pair of conductors near their connection to said casing and means for energizing said cathodes including connections from the exterior of said casing passing through said hollow conductors to said cathodes, said casing being evacuated.

12. A power supply including a coupling circuit for coupling high frequency energy at low potential to said system, an evacuated casing having therein a pair of transmission line sections each including a conductor having an electrical length equal to one quarter of the operating wavelength of a source of high frequency energy with which said system is adapted to be operated, said line sections each being short circuited at one end, said coupling circuit introducing said high frequency energy into said lines near said one end, said conductors each carrying an electron emitting cathode at their free ends, and an anode in operative association with said cathodes.

13. A power supply system including a coupling circuit for coupling high frequency energy at low potential to said system, an evacuated casing having therein a pair of transmission line sections each including a conductor having an electrical length equal to one quarter of the operating wavelength of a source of high frequency energy with which said system is adapted to be operated, said line sections each being short circuited at one end, said coupling circuit introducing said high frequency energy into said line sections near said one end, said conductors each carrying an electron emitting cathode at their free ends, said free ends being closely adjacent, and an anode in operative association with said cathodes.

14. Apparatus for producing high uni-directional voltage from relatively low voltage alternating current including, an evacuated container, rectifier electrodes including an anode and a cathode within said container, a two-conductor transmission line of an electrical length substantially equal to one quarter of the wave length of said alternating current within said container, a coupling between one conductor of said line and said cathode, a coupling between the other end of said one conductor extending through the wall of said container, and excited by said alternating current and an output lead extending from said anode through the wall of said container.

15. Apparatus for producing high uni-directional voltage from relatively low voltage alternating current, including, an evacuated container, rectifier electrodes including an anode and two cathodes within said container, two transmission lines of an electrical length equal to one quarter of the operating wave length of said alternating current within said container, a coupling between one end of each of said lines and a different one of said cathodes, a coupling between the other ends of said lines extending through the wall of said containers and excited by said alternating current and an output lead extending from said anode thru the wall of said container.

JOHN EVANS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,128,750 Kriebel Aug. 30, 1938 2,216,209 Mutscheller Oct. 1, 1940 2,365,855 Atlee Dec. 26, 1944 FOREIGN PATENTS Number Country Date 116,708 Australia Mar. 10, 1943 

